2010 BGD Practical 12 - Third Trimester
- Fetal Neural
- Fetal Respiratory
- Fetal Cardiovascular
- survival issues for early delivery
- fetal weight
- fetal origins hypothesis
BGD Cycle A 2010 Audio - Dr Mark Hill Monday 17th May 2010 3-5pm G2G4.
- Earliest potential survival expected if born
- Respiratory Week 24 to 40 lung histology - terminal sac, end month 6 alveolar cells type 2 appear and begin to secrete surfactant
- saccule - a large thin-walled airspace lined by flattened epithelium present from about 28 weeks gestation to 2 months after birth
- Gonad - male gonad (testes) descending (week 30) Development Animation - Testis Descent
- 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal
- 24 to 26 weeks - (57.9%) had migrated from the abdomen
- 27 to 29 weeks - (16.7%) had not descended to the scrotum
|Testis Descent Failure of descent (cryptorchidism) either unilateral or bilateral testicular descent, occurring in up to 30% premature and 3-4% term males.|
References: Sampaio FJ, Favorito LA. Analysis of testicular migration during the fetal period in humans. J Urol. 1998 Feb;159(2):540-2. | Malas MA, Sulak O, Ozturk A. The growth of the testes during the fetal period. BJU Int. 1999 Oct;84(6):689-92.
Most of the serious illness and mortality is concentrated in the 1 to 2 percent of infants who are born at less than 32 weeks of gestation (week 30) and who weigh less than 1500 g.
Teratogens - Infant Drug Clearance
Teratogen (Greek, teraton = monster) Any agent that causes a structural abnormality following exposure during pregnancy. The overall effect depends on dosage and time of exposure.
The drug clearance data below are only approximate calculated rates for the fetus and infant from NZ Drug Safety in Lactation
|Post-conceptual Age (weeks)||Clearance of Drug (percentage of adults)|
The following information is a detailed timeline of third trimester development and content does not form part of the current practical class.
(Clinical Week 28)
|Clinical third trimester||Sense - Hearing 3rd Trimester - vibration acoustically of maternal abdominal wall induces startle respone in fetus.|
|Respire Month 7 - respiratory bronchioles proliferate and end in alveolar ducts and sacs|
Genital male gonad (testes) descending
|Neural brain cortical sulcation - primary sulci present PMID:11158907|
|Neural brain cortical sulcation - insular, cingular, and occipital secondary sulci present PMID:11158907|
|Birth|| Clinical Week 40
Heart pressure difference closes foramen ovale leaving a fossa ovalis
Thyroid TSH levels increase, thyroxine (T3) and T4 levels increase to 24 h, then 5-7 days postnatal decline to normal levels
Adrenal - zona glomerulosa, zona fasiculata present
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- 2010 BGD: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12
Cite this page: Hill, M.A. (2019, September 16) Embryology 2010 BGD Practical 12 - Third Trimester. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2010_BGD_Practical_12_-_Third_Trimester
- © Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G